Unique utilisation pattern responses of five sympatric ungulates to local phenological gradients

Abstract

Context Ungulate life-history strategies and behaviour are driven by two dominant factors, namely, acquisition of nutrients and avoidance of predation. Although many studies have investigated single species resource/habitat selection, there are still gaps in our understanding of multi-species systems and resource partitioning. Aim We explored the habitat selection of five sympatric resident ungulates in relation to seasonal phenological gradients in a temperate grassland (Northern Great Plains) system. We identified and compared habitat-utilisation strategies across the vegetation-growing season and related to established forage acquisition hypotheses. Methods We collected ungulate detection data during two field seasons (July–October 2018, May–September 2019) across 202 sites and deployed 1202 cameras (29 284 camera-nights). We modelled ungulate detections in relation to normalised difference vegetation index (NDVI) and NDVI slope (rate and direction of change) to learn about ungulate resource selection in four habitat types (grass, prairie dog colonies, forest and riparian). Results We found unique foraging strategies for each of the focal species throughout the growing season (spring, summer, early autumn), which resulted in seasonal partitioning of resources among sympatric ungulate species. Conclusions The temporal and spatial patterns observed emphasise that multiple species can experience the same vegetation phenology and respond differently in their movements and foraging behaviour. At local scales, some ungulates selected for higher forage quantity (selection of higher NDVI) and some for higher forage quality (selection of positive NDVI slope or greening up). Implications The unique foraging strategies presented here indicated that generalisations are problematic when managing wildlife resources and emphasise the need to conduct multi-species studies to understand resource utilisation at local scales. Furthermore, understanding variation in foraging strategies of resident sympatric species can direct management planning where decreased connectivity or loss of migration pathways alters traditional behaviours.